I am currently running a custom Upfront 0.4 and Panino Version: 0.1.6 on a customer site. With no domain mapped (ie https://example.com/customer_name/) the Upfront editor works.
I suspect this is because the Administration URL is not sticking to the customer's domain.
Another thread (https://premium.wpmudev.org/forums/topic/domain-mapping-bug-force-https-setting-in-admin-not-saving?utm_expid=3606929-52.ZpfeUjXqSWOCaoohIqoFQQ.0&utm_referrer=https%3A%2F%2Fwww.google.com) shows where to fix this. However:
I have a discrete problem following this advice. Specifically - The Radio Button/Admin Setting - starts blank - and doesn't save when set... even after a "Options updated." message in the Network Admin > Settings > Domain Mapping Options > Administration mapping > "mapped domain" is set and "Save Changes" is clicked.
I have deleted and re-installed Domain mapping == 126.96.36.199 ==
Here is a screenshot (attached)